Argon is the most common and cheapest of the noble gases. It can be extracted from air by cooling the air down to the point where it liquefies, then doing a fractional distillation of the resulting liquid to isolate the argon fraction. I've seen machines that do this for sale on eBay for a few thousand dollars: Buy you own private argon factory!

Some common light bulbs are filled with argon, while fancy high-intensity ones are filled with krypton or xenon, which allow the filament to burn at a higher temperature. It's also used to fill high-efficiency double-pane windows.

I have a tank of argon gas in my office for filling bottles holding air or moisture sensitive samples: It's cheap and relatively easy to handle, and is therefore commonly used as a shield gas. "Heli-arc" welding is a technique in which an inert gas is blown around the welding tip to protect the hot metal from oxidation. It's named after helium, but actually done using argon, because argon is cheaper.

Ordinary light bulb.
Exotic light bulbs are filled with xenon or krypton, but ordinary everyday ones are filled with argon, because it's cheap. This one happens to be a burned out bulb from a microscope, I'm using it just because it's the right size to fit in the table.Source:Theodore GrayContributor:Theodore GrayAcquired:15 April, 2002Price: DonatedSize: 1.5"Purity: >90%Sample Group:Light Bulbs

Antique reagent flask.
I got a set of five different noble gas flasks on eBay for $13.50, which seemed like a good deal even though the seller described them as "probably empty". I very much doubt, however, that they are empty: At the bottom where the flask meets the tube, there is a tiny inner breakaway seal that is completely intact on all five of them. There's no visible way for the gas to have escaped. I've learned that one normally uses a steel ball, held up with a magnet, to break the seal: When you've hooked up and flushed out all the connecting tubes, you pull away the magnet and the ball drops onto the seal, breaking it and releasing the gas.
After many unworkable suggestions for proving whether the gases were still in there, several people came up with the idea of using a high voltage transformer, such as one finds in those now inexpensive plasma ball novelty lights, to try to set up an arc inside the flask, and identify the gas from the color of the discharge. Whether this is possible is sensitive to the pressure of the gas, which is not known.
Fortunately, it worked beautifully on three out of the five, and proved beyond a reasonable doubt that those three at least contain the gas claimed. The others almost certainly failed because the type and pressure of gas in them does not support an arc, not because they are empty. In fact, if they were empty, I would have gotten an arc, because the arc works through up to about half an inch of ordinary air.
You can see pictures of all the arcs along with a picture of the display stand I built for them (between 10PM and midnight of the evening they arrived) a using some of the same Carlson Maple used for the noble gas tiles on the table.
By the way, isn't it a cute oxymoron: Reagent-grade non-reactive gas.Source:eBay seller tictoxxContributor:Theodore GrayAcquired:28 August, 2002Text Updated:29 January, 2009Price: $3Size: 9"Purity: 99.95%

Mounted arc tube.
In some ways, gases are a pain from a sample point of view. With the exception of chlorine and bromine they all look exactly the same: Like nothing at all. My beautiful set of noble gas flasks is beautiful because of the flasks, not what's in them, which is indistinguishable from plain air or vacuum. (So much so that I got them for a bargain price because the seller thought the were empty.)

But set up an electric current through almost any gas, and things are completely different. The current ionizes the gas, and when the electrons fall back into their orbits, they emit light of very specific frequencies. These spectral lines can easily be seen with even a very cheap pocket spectroscope, and they give the glowing tubes very unusual colors. So unusual in fact that they are basically impossible to photograph. The pictures here simply don't look at all like the real colors of these tubes, which cannot be represented by the limited red, green, and blue mixtures available in computer or printed photographs.

David Franco helped arrange these tubes, which were made by a guy who specializes in noble gas tubes and Geissler tubes (click the source link). I have tubes installed in each of the five stable noble gas spots in the table, hooked up underneath to a high voltage transformer. They are really quite beautiful. On my Noble Rack page I have all the pictures collected, along with pictures of arcs I made in my other collection of noble gas flasks.

Sample from the RGB Set.
The Red Green and Blue company in England sells a very nice element collection in several versions. Max Whitby, the director of the company, very kindly donated a complete set to the periodic table table.

Sample from the Everest Set.
Up until the early 1990's a company in Russia sold a periodic table collection with element samples. At some point their American distributor sold off the remaining stock to a man who is now selling them on eBay. The samples (except gases) weigh about 0.25 grams each, and the whole set comes in a very nice wooden box with a printed periodic table in the lid.

High pressure cylinder.
This cylinder contains 20 cubic feet of argon under about 2000psi of pressure. Or at least it did when I first got it: I use it to purge sample bottles of air-sensitive element samples before re-closing them, so it's slowly getting used up. When it's empty I'll get it refilled: Argon costs about fifty cents a cubic foot, once you've paid for the cylinder and regulator needed to handle it. Those cost a good bit more, but can be reused indefinitely.

Gases like argon, helium, nitrogen, oxygen, carbon dioxide, and of course acetylene are easily available at any welding supply store. They are all set up to re-fill such cylinders on a routine basis (in fact, it's their main business). Larger cylinders are typically leased to you, but small ones like this you buy outright.

Museum-grade sample.
In early 2004 Max Whitby and I started selling individual element samples identical or similar to the samples we use in the museum displays we build. These are top-quality samples presented in attractive forms appropriate to the particular element. They are for sale from Max's website and also on eBay where you will find an ever-changing selection of samples (click the link to see the current listings).

This is a lovely hand-made discharge tube, powered by a small high-voltage transformer. The color is characteristic of the noble gas contained in the tube, and of course the shape spells the element's atomic symbol. In our large periodic table displays we use larger versions of these tubes: The ones photographed here are about 3" tall, but the other ones look basically identical, just bigger.

I chose this sample to represent its element in my Photographic Periodic Table Poster. The sample photograph includes text exactly as it appears in the poster, which you are encouraged to buy a copy of.

Wine preserver.
Some people feel that after a bottle of wine has been opened, it should not be stored with air in it, because this will ruin the taste of the remaining wine. Personally I think the taste of all wine as been ruined already, it's basically grape juice that has gone sour, but that's just me.
Anyway, the solution to the air-in-the-bottle problem, if you think it's a problem, is to purge the air out and replace it with an inert gas, like the argon in this small compressed gas cylinder (the same size as CO2 cylinders used in BB-guns and similar applications). There's a machine available from wine snob catalogs that uses these cylinders for exactly that purpose.
I can't imagine this cylinder holds enough gas to purge more than one bottle of wine, at least not to any high level of purity (to be sure you've displaced all the air from a container, you need to blow at least 10 or more times its volume of inert gas through it). But maybe high purity is not critical, who knows, and why not just drink the whole thing at once if you bothered to open it in the first place?Source: www.chefsresource.comContributor:Theodore GrayAcquired:20 January, 2007Text Updated:21 January, 2007Price: $4Size: 4"Purity: >90%

Antique Violet Ray Machine.
This device, which dates from the 1930's or thereabouts, is basically a lot like one of those novelty plasma ball toys. Modern plasma balls use a high-voltage, high-frequency transformer to create an electric discharge through a mixture of gases in a glass ball. They are purely for entertainment.
This device uses a coil and interrupter to generate the high voltage, and probably contains ordinary air at reduced pressure. It was designed to cure pretty much any disease. This manual is, basically, nonsense, with the possible exception of the treatment of some skin conditions through the antibacterial effects of ozone, which the thing does generate under the right conditions.
Why do I have this machine as an element sample under argon? Because I originally thought, based on reading incorrect reports, that these things were typically filled with argon. In retrospect this is implausible, because all the noble gases were expensive in those days, and would never have been used when plain air works just as well.Source:eBay seller cacheofcoinsContributor:Theodore GrayAcquired:10 March, 2007Text Updated:29 January, 2009Price: $67Size: 12"Purity: 0%Sample Group:Medical

Argon signal lamps.
I'm guessing that these antique bulbs are filled with nearly pure argon, but I don't really know. Connected to a hundred or so volts they produce a characteristic purple-blue glow over the surface of the electrodes. Not enough to create usable light, but perfect as a signal light, the kind of thing that today would be done with an LED or neon indicator light.Source:eBay seller ramblingguyContributor:Theodore GrayAcquired:28 February, 2009Text Updated:12 March, 2009Price: $10Size: 3"Purity: 90%

Argon-filled double-pane window.
Inexpensive insulated double-page windows are often filled with argon gas because it's cheap and helps a bit to increase the insulating properties of the window. It leaks out after a few years.Source:Hardware StoreContributor:Theodore GrayAcquired:28 February, 2009Text Updated:1 March, 2009Price: $30Size: 12"Purity: 80%

Argon gas valve.
This is an ordinary high-pressure (up to three or four thousand PSI) gas regulator meant for gases other than oxygen. I use it on an argon cylinder, so I'm listing it under argon, but mainly it's here to illustrate the general concept of high pressure gas regulators.Source:Claudin Welding SupplyContributor:Theodore GrayAcquired:16 October, 2009Text Updated:18 October, 2009Price: $40Size: 8"Purity: 0%